Many people have indoor plants in their homes, often of a variety of species. Each plant species requires specific climatic conditions for luxuriant growth. Such requirements include the correct amount of light, water, heat, air and nutrients. All these factors are important in the plants' biological processes of photosynthesis, respiration and transpiration.
Photosynthesis is dependent upon carbon dioxide in the air, mineral elements in the soil, water and light. Different plant species have varying requirements for light, depending on the natural sunlight conditions in their countries of origin. Indoors the quantity and quality of light varies in different parts of the same room. Light intensity drops rapidly away from windows. This decrease is too sensitive for the human eye to detect. The amount of light entering a room depends on a number of factors. The size and number of windows are important, but so is the season of the year, the direction that the room faces and other factors such as trees and buildings outside of the window/s. If the position chosen for a plant to grow in is incorrect, adult leaves gradually turn yellow whilst the younger ones remain small and pale. A photoelectric cell is suitable to detect these varying lighting conditions.
Transpiration is regulated by the opening and closing of the stomata of the plants' leaves. The stomata are used in all of the plants' biological processes, to absorb carbon dioxide during photosynthesis and oxygen during respiration. The opening mechanism of the stomata is closely tied to the amount of humidity in the air. If the air is too dry, the plant loses excessive water during transpiration and would therefore need to be watered more regularly than if the humidity level was optimum for the plant. If the humidity is too high, then the plants' stomata will not open sufficiently to absorb oxygen or carbon dioxide. Generally the humidity for indoor plants should remain above 55-60%. This figure naturally varies for different plant species. For example plants with light, soft foliage, such as the maidenhead fern, higher humidity is required, whilst conversely plants with thicker, leathery leaves prefer lower humidity, such as the urn plant. A hygrometer is therefore essential to assure successful plant growth.
Heat as mentioned previously is also an important factor in a plant's growth. Each plant species has optimum temperatures for each phase of its growth, but it also has a biological maximum and minimum temperature. Above or below these temperatures all the metabolic processes of the plant cease. The ideal temperature for most plant growth is approximately 64-75 Farenheiht. The variation between night and day temperatures should not exceed more than 7-9 Farenheight. Greater variations soon damage the plant causing flowers and leaves to fall and foliage to yellow. A thermometer that records the daily maximum and minimum temperatures is important to determining the correct microclimate for a plant.
Watering a plant, which includes the quantity of water in a single watering period as well the frequency of the watering periods, depends upon the microclimate that is created indoors. The microclimate conditions have already been discussed above under light, heat and humidity. Too little water and the plant wilts, but too much water is even worse for a plant because the air in the soil is driven out and consequently the roots suffocate. Correct control of the water content in the plant's soil is essential to the healthy growth of the plant.
Nutrients are also essential to plant growth. A close relation exists between water and nutrients because the roots absorb the plant's food from water. Chemicals essential to the balanced development of plants are nitrogen, phosphorus and potassium.
Other trace elements are also needed. The periodicity and quantity of applying these chemicals vary from one plant species to another. For example the papyrus plant needs to be fertilized every four weeks, whilst the silk oak requires fertilization every two weeks.
Currently most people simply guess when a plant needs watering and fertilization. Some commercial products are available on the market to measure soil humidity, air temperature and light. For example the "Instamatic duo light/water tester" marketed by AMI Medical Electronics, Inc. of Ronkonkoma N.Y. This is an analog handheld device that gives the user a simple meter reading of the soil moisture and light currently available to a plant being tested. The device does not provide an integrated electronic plant husbandry system, as proposed by this invention, that measures all the plant's microclimatic parameters over a period of time and consequently provides the user with an automated notification of a specific plant's required microclimatic conditions, as set out in the above discussion.
This invention aims at electronically monitoring the indoor plants' environment and via a preprogrammed, husbandry program, which contains the required values for proper specific plant species growth, will inform the user of the next required watering for each different plant, the amount of required water and whether or not the current plant's dosage of light and heat is sufficient. It will also notify the user when fertilizer should be added.